In a conventional streaming media service, an RTP (Real-time Transport Protocol, real-time transport protocol) and an RTSP (Real Time Streaming Protocol, real time streaming protocol) are adopted for transmission of streaming media. This type of streaming media service needs a dedicated streaming server, and the streaming server keeps a one-to-one session connection with a client. The streaming server serves as a controller. The client traces a change of a session state. The streaming server adjusts a streaming media transmission speed according to a network bandwidth, and sends media content to the client. However, this type of streaming server is a server for a special purpose, and during streaming media transmission, a firewall is a hinderer that hinders the transmission of the streaming media, thereby causing usage inconvenience.
The web page is widely used, and a WEB server supports HTTP (Hyper Text Transfer Protocol, hyper text transfer protocol) transmission, and therefore, it is a development trend that streaming media transmission is performed by adopting the HTTP, so as to replace the conventional streaming media service. The streaming media transmission performed by adopting the HTTP focuses on a client. A common HTTP file server may be used as a server, and control of a “session” is completed by the client (an HTTP streaming media service has no session but only a series of HTTP requests and responses that are independent of each other). The server sends a file or a certain part of a file to the client only according to a request of the client, and the client needs to clearly indicate a requested file or a certain requested part of a file. In the prior art, to be adaptive to a change of a network bandwidth, the same content is encoded into versions with different rates. Each version is divided into media segments in a chronological manner. These media segments are stored on an HTTP file server, and these media segments may be separately accessed by the client. The client selects a media segment of a different version (rate) according to an actual transmission rate of a network, and may switch transmission among streaming media segments with different rates according to the change of the network bandwidth.
However, when the network bandwidth changes in a larger range, for example, when the network bandwidth is lower than a lowest coding rate of a streaming media segment stored on the HTTP file server, a streaming media transmission service is interrupted if transmission is performed in an existing manner.